Telephone system



P 1944- c. E. LOMAX 2,358,017

TELEPHONE SYSTEM I Filed Jan. 8, 1943 5 Sheets-Sheet 2 FIG. 2

LINE FINDER msTmBuToR 34 llfikmzoe :;1 047g v Q c474\ I R2202 R250TesTfi T 232 CUTOFF C4 212 1 227 247W 205 HST. R 210 zu i INVENTOR.CLARENCE E. LOMAX BY m'm m Mam ATTORNEYS -30o J LANE L156, 33' W7? FIG.3 I WERE]? Sept. 12, 1944. LCM- X 2,358,017

TELEPHONE 5 Y5 TEM Filed Jan. 8, 1943 5 Sheets-Sheet 3 R370 BATTSECRETARY CONNECTOR CENTRAL OFFICE l0 C: SECRETARY OPERATOR K72 dfiAPOSITION. n

INVENTOR. CLARENCE E. LOMAXC BY 1 m wzm ,M m

ATTORNEYS.

Sept. 12, 1944.

C. E. LOMAX TELEPHONE SYSTEM Filed Jan. 8, 1943 5 Sheets- Sheet 4 FIG. 4

LINE FINDER 4| J ,LOCAL 022B LINE CIR.

- LOCAL 29 ,622A 22 25/ DISTRIBUTOR 75 28 7 1 LOCAL FINDER LOCAL L 2CONNECTOR 3:, 0

- INVENTOR. CLARENCE E. LOMAX ATTORNEYS Sept. 12, 1944. E, L MAX2,358,017

' TELEP HONE SYSTEM Filed Jan. 8, 1943 5 Sheets-sheaf. 5 j

SECRETARY LINE CIRCUIT 32 31 /573 R560% R56 R570 CUT 0F SERVICE FIG. 5

' SELECT sw. 520 506 SECRETARY SERVICE fi g 582 SWITCH 7| 3524 l f I 536LINE T HOLD l53l 537 532 x INVENTOR.

CLARENCE E. LOMAX BY mfim wm ATTORNEYS Patented Sept. 12, 1944TELEPHONE-SYSTEM Clarence E. Lomax, Chicago, Ill., assignor to AutomaticElectric Laboratories, Inc., a corpora-.-

tion of Delaware Application January 8, 1343, Serial No. 471,683

23 Claims.

The present invention relates to telephone systems and more particularlyto such systems arranged to render secretarial service to certainsubscriber substations served thereby.

In a conventional telephone system, agencies independent of thetelephone operating company provide a type of service known assecretarial service, whereby certain subscribers, such as doctors,salesmen and others who do not have secretaries and whose duties requirethat they be absent from their ofiices for considerable periods of time,may have calls directed to their substations intercepted and forwardedto the agencies mentioned. A call thus intercepted is answered by asecretary at the agency; and, after the secretary makes inquiry andlearns the desired called subscriber, she gives the calling subscribercertain information in accordance with the prior instructions of thecalled subscriber.

In a telephone system of the type noted the telephone operating companyhas no supervision over the agencies and the apparatus 'usually employedtherein is not well designedto render highly satisfactory secretarialservice.

Accordingly, it is an object of the present invention to provide atelephone system incorporating an improved arrangement including anoperator switchboard under the supervision of the telephone operatingcompany for rendering secretarial service to certain subscribersubstations served thereby.

Another object of the invention is to provide in a telephone systemcomprising a number of ofiices, an improved arrangement for renderingfrom an operator position in the central oflice secretarial service tocertain subscriber substastitute and to discontinue interceptor serviceat certain subscriber substations served thereby,

A further object of the invention is to provide in a telephone system animproved intercepting arrangement, whereby calls extended both to andfrom subscriber substations at which ini type.

lined and additional operating advantages are attained.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood'by reference to the following specification taken inconnection with the accompanying drawings, in which Figure 1 illustratesthe general arrangement of a telephone system embodying thepresentinvention; and ,Figs. 2 to 5, inclusive, taken together,illustrate the details of a system having incorporated therein the fea-'tures of the invention as briefly outlined above.

Description of the apparatusincorporated in the system Referring nowmore particularly to Fig. 1 of the drawings, the telephone system thereillustrated comprises'a central ofiice ID of any suitable type and abranch ofiice 20 of the automatic The central ofiice l0 includes asecretary operator switchboard or position H of the manual type; and thebranch oifice 20 serves a group of automatic subscriber substations,including the subscriber substations Tl, T2, T3 etc. The subscribersubstations in the branch oflice 20 are divided into a first subgroup,including the subscriber substation Tl, which is rendered ordinaryautomatic subscriber substation service, and a second subgroup,including the subscriber substations T2 and T3, which is renderedsecretarial the subscriber. lines 2|, 22 and 23 respectively terceptorservice is enforced are routed to ,an'"

operator position.

Further features of the invention pertain to the particular arrangementof the circuit elements of the system, whereby the abo've-outextendingto the subscriber substations Tl, T2 and T3. Each of the-subscriberlines is provided with a local line circuit individual thereto, thelocal line circuits 24, 25 and 26 being individual to the respectivesubscriber lines 2I-, 22 and 23 respectively extending to the subscribersubstations TI, T2 and T3. Also each of the subscriber lines which isrendered secretarial service is providedrwith a secretary line circuitindividual thereto, the secretary line circuits 32 and 3-3 beingindividual to the subscriber lines '22 and 23 extending to the"subscriber substations T2 and T3 which are rendered secretarial service,Also the branch exchange 20 comprises local automatic switchingapparatus including a number of local links, oneof thelocallinks, beingillustrated as dered secretarial service.

. the branch oflice 20 and the central oflice I and terminating in ajack J I2 at thesecretary opaccess to the subscriber lines extending 'tothe subscriber substations TI T2, T3 etc.; and the local connectors 28etc. also have access to a trunk I5 extending between the branch officeand" the central oflice I0 and terminating in 'a jack J II at thesecretary operator position II.

Further the branch ofiice 20 comprises a number of linefinders 4|, 42etc. having access to the subscriber lines 22, 23 etc. extending to thesubscriber substations T2, T3 etc. which are ren- A line finder' distributor 34 is operatively associated with the line finders 4|, 42 etc.for the purpose of assigning an idle line finder for the use of either acalling or called subscriber line extending vto a subscriber substationwhich is rendered'secretarial comprises a secretaryservice switch'lloperatively connected to a trunk 12 extending between erator positionII. The secretary service switch II has access to the various secretaryline circuits 32, ,33 etc. individually associated with the subscriberlines 22, 23 etc. extending to the subscriber substations T2, T3 etc.which are rendered secretarial service. 7

The central oflice I0 comprises, in addition to the secretary operatorposition II, anumber of secretary connectors 5I, 52 etc. respectivelycor- V responding to the line finders M, 42 etc. and operativelyconnected thereto by means of a number of trunks 6|, 62 etc. extendingbetween Accordingly, the line finder 4| disposed in the branch office 20and the secretary connector 5I disposed in the central office I Darinterconnected by, the trunk Iil. extending therebetween and constitutea linkwhich is utilized for a pur- V pose more fully explainedhereinafter. Similarly,

.noted that the trunks 82, 83 etc. respectively terminating in the jacksJ2, J3 etc, at the scoretary operator position I I respectivelycorrespond to the subscriber lines 22, 23 etc. in the branch office 20respectively extending to the subscriber substationsTZ, T3 etc. whichare rendered secretarial service.

The actual number of-local finder-connector linksprovided inthe branchofiice 20 is determined .by the amount of local traffic therein; whilethe actual number of line findensecretary connector links requiredbetween the branch oflice 20 and the central ofiice I0 is determined bythe peak amount of secretarial trafiic between the branch office 20andthe central office I 0. At this point it is noted that anysubscribersubstation rendered ordinary. service may be converted,

whereby it may be rendered secretarial service,

V. the central oflice I0 and. thebranch ofiice 20.; I

'scribed hereinafter. Preferably, each of the line;

individual thereto in conjunction with the necesary circuit changesrendering the secretary line circuit thus provided accessible to theline finders 4|, 42 etc. and the provision of an additional andcorresponding trunk terminating in a corresponding jack at the secretaryoperator position I I and accessible to the secretaryconnectors 5I, 52etc. In passing, it is noted that the actual number of linevfinder-secretary connector links required between the branch office 20'and the central oifice I0 will be only a minor fraction of the number ofsubscriber substations in the branch oflice 20 rendered secretarialservice. a

In the central ofiice I0, the secretary operator position II comprises,as shown in Fig. 3, in addition to the jacks J2, J3, JI I, JIZ etc.,position apparatus not shown; whereby the operator thereat may answercalls on the trunks 62, 83

etc. and the trunk I5 and may control, via the trunk 12 the secretaryservice switch II in the branch ofiice 20. Also associated with thejacks J2 and JII aresignal lamps L382 and L38l, respectively, which areutilized for a purpose more fully explained hereinafter.

Preferably, each of the secretary connectors in the central oilice I0 isidentical to the secrek tary connector 5| which comprises, as shown inFig. 3, a switching mechanism 300 of the Strowger type, including awiper set provided with three wipers 30I, 302 and 303 supported for bothvertical and rotary movements, and an associated semi cylindricalcontact bank provided with ten vertically spaced-apart levels of contactsets arranged in circumferentially spaced-apart relation. Also theswitching mechanism 300 includes a vertical magnet M304 for driving thewiper set step by step in the vertical direction away from its normalvertical position, a rotary magnet M305 for driving the wiper set stepby step in the rotary direction away from its normal rotary position,and a release magnet M306 for releasing the wiper set and for causing-itto be returned to its normal rotary and vertical relay R350, a linerelay R360 and a battery reverse relay R310; and a control networkconnected and arranged in a manner more fully definders in the branchofifice l0 is identical to the line finder M which comprises, as shownin Fig.4, a switching mechanism 400 of the Strowgertype, including awiper set provided with three wipers 40I, 402' and 403supported for bothvertical and rotary movements, and an associated -semicylindricalcontact bank provided with ten vertically spacedapart levels of contactsets arranged in circumf ment,1 and an associated vertical controlcontact bank. Further theswitching mechanism 400 includes'a verticalmagnet M405 ;for driving the I wiper setand the'vertical control wiper404 step by step in the vertical direction away from their normalvertical positions; a rotary magnet M401" for driving the wiper set stepby step-in the rotary merely by the provision of a secretary linecircuit "direction away from its normal rotary Position,

and a release magnet M409 for releasing the wiper set and the verticalcontrol wiper 404- and for causing the wiper set to be returned to itsnormal rotary and vertical positions and for causing the verticalcontrol wiper 404 to be returned to its normal vertical position; Alsoassociated with the switching mechanism 400 are two sets of switchsprings S4l0 and S413 which are actuated when the wiper set is moved onestep in the vertical direction away from its normal vertical positionand a set of switch springs $414 which is actuated when the wiperset ismoved eleven steps in the rotary direction away from its normal rotaryposition. Further the line finder 4| comprises a repeating coil 435; arelay group, including a pulse relay R420, an answer relay R430, a startrelay R440, a cutoff relay R450 and a test relay'R460; and a controlnetwork connected and arranged in a manner more fully describedhereinafter.

In the branch ofiice 20, the line finder distributor 34 comprises, asshown in Fig. 2, a switching mechanism 200 of the rotary type, includingfive wipers to 205, inclusive, provided with individually associatedcontact banks, and a magnet M206 for driving the wipers noted in theclockwise direction; the switching mechanism 200 having access via thecable 410 to'the various line finders 4|, 42 etc. Also the line finderdistributor 34 comprises a relay group, including a start relay R2l0, atest relay R220, a step relay R230, a transfer relay R240, and a "cutoffrelay R250; and a control network connected and arranged in a mannermore fully described hereinafter.

Preferably, each of the secretary line circuits in the branch office 20is identical to the secretary line circuit 32 individually associatedwith the subscriber line 22 extending to the subscriber substation T2which is rendered secretarial service. The secretary line circuit 32comprises, as shown in Fig. 5, a relay group, including a cutoff relayR560, a start relay R565 and a service relay R510; and a control networkconnected and arranged in a manner more fully described hereinafter. Inthe branch ofiice 20, the local line circuits 24, 25 etc. are ofconventional connection and arrangement and are. of any suitable for'm.Also in the branch office 20 the local links are of any suitable type;however, it is preferable that both the local finders and the localconnectors thereof be of conventional Strowger types of standardconnections and arrangements. Moreover, in the branch oflice 20, thelocal distributor 29 is of any suitable form and may be quite similar inconnection and arrangement to the line finder distributor 34'illustrated.

In the branch ofiice 20, the secretary service switch H comprises, asshown in Fig. 5, switching mechanism 500 of the Strowger type, icludinga wiper set provided with six wipers 50l to 506, inclusive, supportedfor both vertical and rotary movements, and an associatedsemicylindrical contact bank provided with ten vertically spaced-apartlevels of contact sets arranged in circumferentially spaced-apartrelation, Also the switching mechanism 500 includes a vertical magnetM50!v for driving the wiper set step by step in the vertical directionaway from its normal vertical position, a rotary magnet M508 for drivingthe wiper set step by step in the rotary direction away from its normalrotary position, and a release magnet M509 for releasing the wiper setand for causing it to be returned to its normal rotary and verticalpositions. Also asill sociated with the switching mechanism 500 are twosets of switch springs S5l0 and S5l3 which are actuated when the wiperset is driven in the vertical direction one step away from its normalvertical position. Also the secretary service switch H comprises aselect switch 520 of the minor type, including a single wiper 52Lprovided with an associated contact bank, a rotary magnet M522 fordriving the wiper noted step by step in the counterclockwise directionaway from its normal rotary position, and a release magnet M523 forreleasing the wiper noted and for causing it to be returned in theclockwise direction back into its normal rotary position. Alsoassociated with the select switch 520 is a set of switch springs S524which is actuated when the wiper noted is driven in the counterclockwisedirection one step away from its normal rotary position. Further thesecretary service switch H comprises a relay group, including a linerelay R530, a hold relay R535, two transfer relays R540 and R545, aswitch relay R550, and a control relay R555; and a control networkconnected and arranged in a manner more fully described hereinafter.

A better understanding of the connection and arrangement of the systemwill be facilitated from ,a consideration'of the detailed operation ofthe various pieces of apparatus incorporated therein incident tohandling local traffic in the branch ofiice 20 and secretarial trafficbetween the branch ofiice 20 and the central office 10, as will appearhereinafter.

, Institutirzg secretarial service at a subscriber substation in thebranch office When a subscriber ata subscriber substation in the branchoffice 20 which is rendered secretarial service desires to utilize thisservice, he first extends a call to the secretary operator position Itin the central office i0 and advises the operator thereat concerning anyinformation which is to be givento other subscribers calling the subinhis absence.

ial service at the subscriber substation T2, the subscriber thereatremoves the receiver from its associated switchhook; whereby the localline circuit 25 is controlled over the subscriber line 22. Morespecifically, the local line circuit 25 controls thelocal distributor29, whereby an idle local link, such, for example, as the local linkillustrated is assigned and the local finder 21 thereof is operated toseize the subscriber line 22 extending to the calling subscribersubstation T2. When the local finder 21 seizes the subscriber line 22,,the

subscriber line 22 is marked as busy via the control conductor C22Bthereof to the local connectors having access thereto and the localconnector 28 is conditioned to be operative in response to one or moredigits received over the calling subscriber line 22. The subscriber'atthe calling subscriber substation T2 then dials one or more digits'overthe subscriber line 22, whereby the local connector 28 is operated toselect the trunk 15 extending to the secretary operator position H inthe'central ofiice l0. The local connector '28 tests the idle or busycondition of the selected trunk' 15 causing busy tone current to bereturned over the subscriber line 22 to the calling subscribersubstation T2 in the event the trunk 15 is busy at this; time. On theother hand, in the event the trunk 15 is idle at this time, the localconnector '28 operates to seize the trunk 15, "whereby ground potentialis applied tothe control conductor C15A thereof in order to mark thetrunk 15 as busy to the other local connectors having access thereto andto complete an obvious circuit, including the contacts ofthe jack JII,for illuminating the signal lamp L38I. The H lumination of the signallamp L38I indicates the presence of'a call on thetrunk,15; 'whereby theoperator at the secretary operator position I I answers the call byinserting the answer plugv of the cord circuit into the jack J IIeffecting the extinguishment of the signal lamp L3! and completing anobvious connection between the calling subscriber substation T2 andtheteleph one instrument at the secretary operator position II. Thesubscriber at the calling subscriber substa tion T2 then passes to theoperator at the secre tary operator position llthe information which isto be given to other subscribers callingthe subscriber substation T2 inhis absence. Subsequently, when both the subscriber at the callingsubscriber substation T2 replaces the receiver upon its associatedswitchhook and the operator at the secretary operator position IIwithdraws the answer plug of the cord circuit from the jack JI I, thelocal finder 21 and the local connector 28 are released, whereby boththe subscriber line 22 extending to the subscriber substation T2 and thetrunk 15 terminating in the jack JII at the secretary operator positionII are rendered idle Vto'the local connector having access thereto.

The operator at the secretary'operator position 'I I then inserts thecall plug of the cord circuit into thejack J I2 terminating the trunk 12extending between the central office I and the branch office 20, wherebyan obvious circuit is completed for energizing in series the upper andlower windings of the line relay R530 in thesec- :retary service switchH in the branch oflice 20.

as explained more fully hereinafter; while the second and third digitsare effective to operate 1 the switching mechanism 500, thereby toselect the particular secretary line circuit associated 'With thesubscriber line extending to the subscriber substation at whichsecretarial service is to be instituted or discontinued as the, case maybe. More particularly, in the present example, in order to institutesecretarial service at the subscriber substation T2, the three digitsidialed are 1, 2 and 2; the first digit 1 indicating that secretarialservice is to be instituted at the subscriber substation T2 and thesecond and third digits 2 and 2, respectively, identifying the secretaryline circuit 32 individual to the sub- ,scriber line 22 extending to thesubscriber substation T2. 7 V V i ,More particularly, the line relayR530 follows the single impulse of the'first digit 1 restoring and thenreoperating. Upon restoring, the line relay R530 interrupts, at thecontacts 53I, the

previously mentioned circuit for energizing the windingof the hold relayR535, andcompletes, at the contacts 532, a circuit, including thecontacts 531," the contacts 5 of the set of switch-springs "S5I0 and thecontacts 548, for energizing the tracedcircuit'for energizing thewinding of the transfer-relay R540 in series with the rotary magnetM522. Thehold relay R535 and the transfer relay R540 are of thesloW-to-release type; whereby the relays mentioned do not restore duringimpulsing. At this time the rotary magnet M522 restores and the wiper52I of the selectswitch 520. engages the first contact in the associatedcontact hank connected to the wiper, I 50I of the wiper set of theswitchingmechanism V 500,. for a purpose more fully explainedhereinafter. Also when the wiper'52I of the select switch 520 is drivenone step in the counterclock- Wise directionaway from itsnormal rotaryposition, the set of switch springs S524 is actuated into engagement,thereby to prepare. a circuit traced hereinafter for energizing thewinding of the transfer relay R545. Shortly following the conclusion ofthe first digit 1 the transfer relay R540 restores, thereby to complete,at the contacts 54I, the'previ0us1y mentioned circuit including thecontacts 536 and the set of switch springsS524, for energizing thewinding of the transfer relay R545. When thus energized the transferrelay R545 operates to co'mplete, at the contacts 545, an obviousholding circuit, including the contacts 535, for energizing the windingthereof. {Also the transfer'relay R545 interrupts,

at the contacts 548,a further point in the previously traced circuit forenergizing the winding of the transfer relay R540 in series with therotary magnet M522 of the select switch 520, andrprepares, at thecontacts 541, a circuit traced hereinafter for energizing the winding ofthe transfer relay R540 in series with the vertical magnet 'M501 oftheswitching mechanism 500..

' The line'relay R530 then follows the second digit 2, thereby tocomplete, at the contacts 532; 'the first time it restores, thepreviously mentioned circuit, including the contacts 531, the contacts5i I of the set of switch springs S5I0 and the contacts 541, forenergizing the winding of the transfer relay R540 inrseries with'thevertical magnet M501; whereby the transfer relay R540 reoperates and thevertical magnet M501 operates wiper set of ,the switching mechanism 500is driven one step in the vertical direction away from its normalvertical position, the sets of switch springs S5I0 and S5I3' areactuated More particularly, the set of switch springs S5I0 is actuated,thereby to interrupt, at the contacts 5Il thereof, a further point inthe previously traced circuit'for energizing the winding of the transferrelay R540 in series with the vertical magnet M501 and to prepare, atthe contacts'5l'2 thereof, an alternative circuit traced hereinafter forenergizing the winding of the transfer relay R540 in series with thevertical magnetM501. The set of switch springs vS5I3 is actuated intoengagement, thereby to' prepare multiple circuits traced hereinafter forenergizing the release magnets M523 and M509 of the select switch 520and the switching mechanism 500, respectively. The next time the linerelay R530 restores it completes, at the contacts 532, the previouslymentioned alternative circuit, including the contacts 531, the contacts5I2 of the set of switch springs S5l0, the contacts 542 and the contacts541, for energizing the winding of the transfer relay R540 in serieswith the vertical magnet M501. Accordingly, at this time, the line,relay R530 follows the impulses of the second digit 2, where by the holdrelay R535 and the transfer relay R540 remain operated during impulsingand the wiper set of the switching mechanism 500 is driven two steps inthe vertical direction away from its normal vertical position. Shortlyfollowing the conclusion of the second digit 2 the transfer relay R540restores, thereby to interrupt, at the contacts 542, a further point inthe previously traced alternative circuit for energizing in seriesthewinding of the transfer relay R540 and the vertical magnet M501; Alsothe transfer relay R540 prepares, at the contacts 543, a circuit tracedhereinafter for energizing in series the winding of the control relayR555 and the rotary magnet M508 .of the switching mechanism 500.

- The line relay R530 then follows the impulses of the third digit 2,thereby to complete each time it restores, at the contacts 532, thepreviously mentioned circuit, including the contacts 531, the contacts512 of the set of switch springs S5l0 and the contacts 543 and 553, forenergizing the winding of the control relay R555 in series with therotary magnet M508, whereby the control relay R555 operates and therotary magnet M505 operates and restores twice in order to drive thewiper set of the switching mechanism 500 two steps in the rotarydirection away from its normal rotary position. At this point it isnoted that the control relay R555 is of the slow-to-release type,whereby the latter relay and the hold relay R535 remain'operated duringimpulsing. At the conclusion of the third digit 2, the line relay R530remains operated and, shortly thereafter, the control relay R555restores. At this time the wiper set of the switching mechanism 500engages the 2 up 2 in contact set in the associated contact bank. Uponrestoring, the control relay R555 completes, at the contacts 556, acircuit, including the contacts 536, the wiper 52I of the select switch520 and the engaged first contact in the associated contack bank, thewiper 501 of the wiper set of the switching mechanism 500 and theengaged contact in the associated contact bank, the conductor C58! andthe resistor 513, for energizing the upper winding of the switch relayR550 in series with the winding of the service relay R510, the servicerelay R510 being in the secretary line circuit 32 individual to thesubscriber line 22 extending to the subscriber substation T2. When thisseries circuit is completed the switch relay R550 operates to complete,at the contacts 552, an obvious holding circuit, including the contacts536, for energizing the lower winding thereof. Also the switch relayR550 interrupts, at the contacts 553, a further point in the previouslytraced circuit for energizing the winding of the control relay R555 inseries with the rotary magnet M508, thereby positively to preventfurther operation of'the switching mechanism 500 at this time. Furtherthe switch relay R550 completes, at the contacts 551, an obvious pathfor short-circuiting the upper winding thereof,

whereby-a low resistance circuit substantially identical to that tracedabove is completed for energizing the winding of the service relay R510in the secretary line circuit 32.

When thus energized the service relay R510 operates to complete,-at thecontacts 51!, an obvious holding circuit, including the resistor 513,for energizing the winding thereof. Also the service relay R510completes, at the contacts 512, an obvious connection "between thewinding of the start relay R5155 in the secretary line circuit 32 .andthe control conductor C22B of the subscriber line 22 extending to thesubscriber substation T2,1for-a purpose more fully explainedhereinafter. At this time, secretarial service has been instituted atthe subscriber'substation T2 in the branch office 20 by the operator atthe secretary operator position II in the centraloflic'e l0 over thetrunk 12 by the operation of the -secre-,

.tary service switch 1| above described. After the operator at thesecretary operator position H has thus instituted secretarialqservice atthe subscriber substation T2 she withdraws the call plug of thecordcircuit from the jack J12, there'- by to interrupt the previouslytraced circuit for energizing in series the upper and lower windings ofthe line'relay R530 in the secretary service switch 11 over the trunk12, whereby the latter relay restores. Upon restoring, the line relayR530 interrupts, at the contacts 53!, the previously'mentioned circuitfor energizing the winding of the hold relay'R-535, thereby to cause'thelatter relay to restore shortly thereafter. 'Upon restoring, theholdrelay R535 interrupts, at the contacts 536, the previously tracedmultiple holdjing circuits for energizing the winding of the transferrelay R545 and the lower winding of the switch relay R550, thereby tocause the relays mentioned to restore. Also the hold relay R535completes, at the contacts 538, the previously mentioned multiplecircuits, including the .contacts 532 and the set of switch springsS513, for en'- ergizing the release magnets M523 'andiM509. When thusenergized the release magnet M523 operates, thereby to release the wiper52l of the selectswitch 520 and'to cause it to be returned in theclockwise 'direction'back into its normal rotary position. When thusenergized the release magnet M509 operates, thereby to release the wiperset of the'switchingmechanism 500 and to cause it to be returned to itsnormal rotary and vertical positions. When the switching mechanism500 isthus released the sets of switch springs S5l0 and S5I3 are actuated.More particularly, the set of switch springs S5l 3 is actuated intodisengagement, thereby to interrupt the previously tracedmultipleicirouits for energizing the release magnets M523 and M509 in'order to cause these release magnets to restore. At this time thesecretary service switch 1lis completely released.

Rendering secretarial service to a subscriber substation in the branch ofice Considering now the manner in which secretaria'l service .isrendered a subscriber substation, such, for example, as the subscribersubstation T2 in the branch office, 20,'afte'r secretarial servicethereat has been instituted in the inanner previously explained, it isagain noted that, in'the secretary line circuit 32 individual to thesubscriber line 22 extending to the subscriber subscriber T2, theservice'relay R510 occupies its operatedposition and the winding of thestart relay R565 is connectedto the control conductor 6 0223 of thesubscriber line 22. At thistime a call may be initiated at any'calling.subscriber substation in the branch office 20, such,'for example, as thesubscriber substation T|,'and extended to the called subscribersubstation T2;

whereby secretarial service is rendered, asexplained more fully'below.More particularly, the subscriber at the calling subscriber substationT| removes the receiver fromits associated switchhook; whereby thelocalline circuit 24 is con trolled over the subscriber line 2|.)MOrespecifically, the local line circuit 24- controls the localdistributor 29, whereby an idle local link, such, forexample, as thelocal link illustrated, is assigned and the local finder 21 thereof isoperated to seize the subscriber line 2| extending to the callingsubscriber substation Tl. When the local finder 21 seizes the subscriberline 2|, the subscriberline 2| is marked as busy via the controlconductor C2|B thereof to the local connectors having access thereto andthe local connector 28 is conditioned to be operative in response totwo'digits received over the calling subscriber line 2 The subscriberiatthe calling subscriber substation Tl then 'dails two digits over thesubscriber line 2|, whereby the local connector 28 is operated'toselectthe subscriber line 22 extending to the called subscriber substation T2.The local connector 28 tests the idle or busy con dition of the selectedsubscriber line 22, causing busytone current'to be 'returned over thesubscriber line 2| to the calling subscriber substaof' battery potentialto the control conductor 0220 of the subscriber line 22 respectivelymark the vertical and rotary positions of the various contact sets inthe line finders 4|, 42, etc. terminating the subscriber line 22extending to the called subscriber substation T2. Also the applicationof ground potential to the mark conductor C418'completes a circuit,including the resistor 208, for energizing the winding of the startrelay R2 0 in the link finder distributor 34, thereby to causethe latterrelay to operate? At this point it is noted that the magnet M206 of theswitching mechanism 200 incorporated in the line finder distributor 34is normally connected via the contacts 201 and 222 to the wiper 202 ofthe rotary switching mechanism 200, which wiper normally engages acontact in the associ-- sociated line finder is respectively idle orbusy.

tion Tl in the event the called subscriber sub-- station T2 is busy atthis time. On the other hand, in theevent the called subscribersubstation T2'is idle at this time, the local connector 28 operates toseize the subscriber line 22, whereby ground potential is applied to thecontrol conductor C22B thereof in order to mark the subscriber 'line 22as busy to the other local connectorshaving access thereto and to causeringing current to be "projected over the'line conductors of thesubscriber line 22 extending to the called subscriber. substation T2,whereby the ringer thereat is operated. However, in the present example,'thegsubscriber at the called subscribersubstation T2 is absent and thecall there'- to'is not'answered at the called subscriber substation T2;rather, the call is answered at the secretary operator position H in thecentral of.-

fice I0, as explained more fully below.

The application of ground potential to the control conductor C2213 ofthe subscriber line.22 ex.-

tending to the called subscriber substation T2 also completes an-obvious circuit, including the contacts 512, for energizing the windingof the anobvious path'for applying battery potential by way of thewinding of thecutofi'relayR560 in the secretary line circuit 32 to thecontrol conof the line finder 4| in the cable 410. a This apductorC22Cof the subscriber line 22 appearing in the contact banks of thevarious line finders 4|, 42 etc. The application of ground'potential tothe mark conductor C418 and'the application Thus it will be understoodthat, when a line finder 4| etc. is rendered busy, ground potential isapplied to the associated guard conductor'C412 etc. and consequently tothe wiper202 of the switching mechanism 200 in'th'e e'ventthewiper'mentioned engages the contact in the associated contact bankterminating the guard conductor mentioned] In this event, groundpotential 'applied to the wiper 202 of the switching mechanism 200completes an-obvious circuit, including the contacts 222 and 201; forenergizing'the magnet'M206, whereby the latter'mag'net operates tointerrupt, at the contacts 201, the previously traced circuit forenergizingthe magnet M206 and to condition the wipers noted of theswitching mechanism 200 to be driven one step in the clockwisedirection. The magnet M206 then restores, whereby the wipers noted ofthe switching mechanism 200 are driven one step in the counterclockwisedirection and the magnet M206 is reconnected, at the contacts 201, tothe Wiper 202 of the switching mechanism 200; whereby .the next linefinder 4|,242 etc. selected by the switching mechanism 200 atthis timeis tested in order to determine the-idle or busy condition the linefinder" 4| is idle' atthis time and that,

the switching mechanism 200'incorporated in the line finder distributor34 has operated to select the conductors extending thereto,battery'potential is applied by way ofthe' lower winding'of Q the testrelay R460 in the "line finder 4|, the

contacts.4|| of the set of switch springs SM 0 and the contacts 444 tothe guard conductor C412 plication of battery'potenti'al to theguardconductor C412 of the line finder 4| in thecable 410 completes a pathsubstantially identical to that previously traced, including thecontacts 201 and 222 and the wiper 202 of the switching mechanism'200Iand the engaged contact in the associ ated contact bank, forshoIt-circuiting in series the line finder 4! is preselected thereby foruse at this time. 1

Upon operating, the start relay R210 completes,

at the contacts 2 I2, an obvious circuit, including the contacts 241 and201, for energizing the 'winding of the test relay R220 in series'withthe mage net M206, whereby the test relay R220 operates. However, themagnet M206 does not operate due to the high series resistance of thewinding of the test relay R220. Upon operating, thetest relay R220completes, at the contacts 221, an ob vious holding circuitsubstantially identical-to that previously traced for energizing thewinding thereof. in series with the magnet 'M206. Also the test relayR220 interrupts, atthe contacts 222, the previously traced originalconnection between the magnet M206 and the wiper 202 of the switchingmechanism 200, and completes, at the contacts 223, an obviousalternative connection between the magnet M206 and the wiper 202. Alsothe test relay R220 completes, at the contacts 221, an obvious path,including the pontacts 2H and the wiper 201 andthe engaged contact inthe associated contact bank, for ap-' plying ground potential tothestart conductor C415 in the cable 410, thereby to completean obviouscircuit for energizing the winding of the start relay R440 in thepreselected line finder 4|, whereupon the latter relay operates. Furtherthe test relay R220 completes, at the contacts 224, a path, includingthe contactsf23lv and 24! and the wiper 203 of the switching mechanism200 and the engaged contact in the associated contact bank, for applyingground potentialto the vertical conductor C416 in the cable 410; andcompletes, at the contacts 226, a connection, including the-contacts246, between the winding of the cutoff relay R250 and the winding of thestep relay R230, the winding of thestep relay R230 being connected tothe interrupter conductor C414 in the cable 410. I

Upon operating, the start relay R440 in the line finder 4| completes, atthe contacts 44l, a circuit for energizing in series the windings of theanswer relay R430 in the line finder 4]. and the windings of the. linerelay R360 in the secretary connector 5! via the trunk 6|. Theabove-mentioned circuit extends v from ground by way of the lowerwindingof the line relay R360, the contacts 314, one of the lineconductors of the trunk 6!, the contacts 42'! and 441, the winding 431of :the repeatingcoil 4135, the windings of the answer relay R430,, .thewinding 436 of the repeating coil 435, the other line conductor of thetrunk '61, the contacts 312 and the upper winding of the line relay R360to bat tery; When this series loop circuitis completed the line relayR360 in the secretary connector 5| operates; however, the answer. relayR430-in 'the line finder 4| does not operateas-the latter Also the startrelay is of the'polarized type. relay R440 completes, at the contacts442, an obvious circuit for energizing the lower winding of the testrelay R460, thereby to render the latter relay exceedingly fast tooperate when -the upper winding thereof is subsequently energized,

. the test relay R460 being of the polarized-type.

Further the start relay R440 completesqat the contacts 441, an obviouspath, including theco-ntacts 451, between the vertical magnet M405 ofthe switching mechanism 400 and the vertical conductor C416 in the cable410,;wherebythe vertical magnet M405 is energized and operates.

Upon operating, the vertical magnet M405 drives the wiper set of theswitchingimechan'ism400s16 one. step in the vertical direction away fromits normal vertical position, and completes, atthe contacts 406, anobvious path for applying ground potential to the interrupter-conductorC414 in the cable 410. When the wiper set of the switching, mechanism400 is driven one step in the vertical direction away from its normalvertical position, the sets of switch'springs S4l0 and S4|3 are actuatedfor apurpose more fully erating, the ,step relay R230 interrupts, at thecontacts 23!, the previously traced path for applying ground potentialto the vertical conductor C416 in the cable 410, thereby to interruptthe previously traced circuitfor energizing the vertical magnet 'M405,whereupon the latter magnet restores, thereby to interrupt, at'thecontacts 406, the previously mentioned path for applying groundpotential to the interrupter conductor C414 in the cable 410. 'Whenground potential is removed from the interrupter conductor-C414 thepreviously traced circuits for energizingin multiple the windings of thestep relayfiR230 and the cutoff relay R250 are interrupted,-whereby thestep relay R230 restores. However, the cutoff relay R250 does notrestore immediately as it is of the slow-to-releasetype Upon restoring,the step relay R230recomp'letes, at the contacts 23l, the previouslytraced circuit for energizing the vertical magnet M405, wherebythe'latter magnet reoperates, thereby to drive the wiper set of theswitching mechanism 400 an additional step in the vertical directionaway from its normalvertical position. Also, upon reoperating, thevertical magnet M405 recompletes, at the contacts 406, the previouslytraced circuits for energizing in multiple the windings of thestep'relay R230 and the cutoff relay R250, whereby the step relay R230reoperates shortly thereafter and the cutoff relay R250 is retained inits operated position as it is of the slow-.to-release type.Accordingly, it

will be understood that the vertical magnet M405 and the step relay R230interact in the manner described above, whereby the cutoff relay R250 isretained in its operated position and thevertical magnet -M405 andthestep relay R230 operate and restore alternately; whereby the wiper setof the switching mechanism 400 is driven step by step in theverticaldirection away from its normal vertical position.

More particularly, the wiper set and the vertical control wiper 404 ofthe switching mechanism 400 aredriven'step by step in the verticaldirection two"'s'tepss, in the present example, whereupon the verticalcontrol wiper 404 engages the second contact in the associated Verticalcontrol contact bank terminating the markconductor C418 having groundpotential thereon; whereby ground potential on'the mark conductor C418is applied to the test conductor C41l in the cable 410. This applicationof ground potential to the test conductor C41l in thecable 410 completesa circuit, including the wiper204 of the switching and the groundedinterrupter conductor C414 in the cable 410, for short-circuiting thelower winding of the transfer relay R240 prior to the completerestoration of the vertical magnet M405 to remove ground potential atthe contacts 406 from the interrupter conductor C414. However, when thevertical magnet M405 restores to interrupt, at the contacts 406, theapplicationof ground potential to the, interrupter conductor ,C414 inthe cable 410, the above-traced path for short-circuiting the lowerwinding'of the transfer relay R240 is interrupted; whereupon a circuit 7is completed for energizing the lower winding of the transfer relay R240in series with the lower winding of the step relay R230. Theabove-mentioned circuit extends from the grounded test conductor C41! inthe cable 410 by way of the wiper 204 of the switching mechanism 200 andthe engaged contact in the associated contact bank, the contacts 245,the lower winding of R240,

the contacts 226 and the winding of R230 to battery. Also a multipleholding circuit is completed for energizing the lower'winding of the atransfer relay R240 in series with the winding of the cutoff relay R250;the last-mentioned circuit including the contacts-246 and 245 and thewiper 204 of the switching mechanism 200 and the engaged contact in theassociatedcontact bank and a the grounded test conductor C41l in thecable 410. When the lower winding of the transfer relay R240 is thusenergized the latter relay op 'erates shortly thereafter, the transferrelay R240 being of the slow-to-operate type. Upon operating, thetransfer relay R240 completes, at the contacts 243, an obvious holdingcircuit, including'the contacts 225, for energizing the upper windingthereof. Also the transfer relay R240 interrupts, at the contacts 2, afurther point 7 in the previously traced path for applying groundpotential to the vertical conductor C416 in the cable 410, and prepares,at thecontacts242, a point in a path traced hereinafter for applyingground potential to the rotary' conductor C413 in the cable .410. Alsothetransfer relay R240 interrupts, at the contacts 245, the previouslytraced circuitsfor energizing the lower winding of the'transfer relayR240 in series multiple relation with respect to the windings of thestep relay R2 and the cutoff relay R250,'interrupts, at the contacts246, a further p'ointiin the previously plete an obvious circuit,including the contacts 446" and 465, for energizingthe rotary magnetM401. When thus energized the rotary magnet M401operates, thereby todrive the wiper set of the switching mechanism'400 one step in therotarydirection away from its normal rotary position; andcompletes, atthe contacts 408, an

obvious alternative 'path for applying ground potential to theinterrupter conductor C414in the cable 410. This application of groundpotential to the interrupter conductor C414 completes the The step relaying of the step relay R230, thereby to cause the latter relay to operateshortly thereafter; however, the previously traced circuit forenergizing the winding of the cutoff relay R250 is not com- I pleted dueto the operated position of the transfer relay R240. Upon operating, thestep relay R230 in order to cause the latter relay to restore. Uponrestoring, the step relay R230 recompletes, at the contacts 231, thepreviously traced circuit for energizing the rotary magnet M401, therebyto cause the latter magnet to reoperate and drive the wiper set of theswitching mechanism 400 an additional step in the rotary direction awayfrom its'normal rotary position. Thus it will be under- ,stood that therotary magnet M401 and the step relay R230 interact in the mannerdescribed above, whereby the wiper set of the switching mechanism 400 isdriven step by step in'the rotary direction away from its normal rotaryposition. In the present example, the wiper set of the switchingmechanism 400 is driven two steps in the rotary direction away from itsnormal rotary position, whereupon the wipers noted thereof engage thecontact set in the associated contact bank terminating the conducors ofthe subscriber line 22 extending to the called subscriber substation T2.7 r

When the wiper set of the switching mechanism 400 engages the contactset in the associated contact bank terminating the conductors of thesubscriber line 22, a series circuit isrcompleted for energizing thewinding of the cutoff relay R560 in the secretary line circuit 32individual to the subscriber line 22 and the upper winding of thetestrelay R460 in the line finder This circuit extends fr0m the groundedtest conductor C41l in the'cable 410 by way of the upper winding ofR460, the wiper 403 of the wiper set of th switching mechanism 400 andthe engaged contact in the associated contact bank,

the control conductor 0220 of the subscriber line 22, the contacts 561and the winding of R560 to battery. When this series circuit iscompleted the test relay R460 operates exceedingly fast, as

it is of the polarized type, to complete, atthe' contacts 462, anobvious path, including the contacts 442 and the grounded test conductorC41! in the cable 410, for short-circuiting the upper ,.previouslytraced'circuitlfor energizing the wind- "15 winding thereof, and anobvious path; including the contact 442, for applying direct groundpotential to the wiper 403 of the wiper set of the switching mechanism400 and consequently to the control conductor C220 of the subscriberline 22, whereby a low resistance circuit substantially identical tothat previously traced'is completed 7 for energizing the winding of thecutoff relay R560 in'the secretary line circuit 32. When thus energizedthe cutoff relay R560 operate to complete, at the contacts 562 and 563,a holding circuit, including the contacts 512 and the, grounded controlconductor 0223 of the subscriber line 22, forenergizing the windingthereof; Also the cutoff relay R560 completes, at the contacts 563, an

obvious path, including the contacts 512, for connecting the groundedcontrol conductor C22B of the subscriber line 22 to the contro1conductor 022C of the subscriber line 22; thereby to comfinder -4 pleteanalternative holding'circuit, including the wiper 403 of the'wiper-setof-the switchingmechanism 400 and the engaged contact in theassociated contact bank .and the contacts 462, for energizing the lowerwinding of the test relay R460 in order to retain the latter relay inits operated position subsequent to the restoration of the start relayR440, as explained more fully hereinafter. Also the cutofi relay R560interrupts, at the contacts '56I, the previously traced path forapplying ground potential to the mark conductor C418, thereby tointerrupt .the previously traced circuit for energizing the winding ofthe start relay R2 l in the line finder distributor 34 in order to causethe latter relay to restore.

AlsO, upon operating, the test relay R460 interrupts, at the contacts465, a further point in the previously traced circuit for energizing therotary magnet M401, thereby positively to prevent further operation ofthe latter magnet, whereby further operation of the wiper set of thswitching mechanism 400 is positively prevented at this time. ,Also thetest relay R460 completes, at the contacts 46|, anobvious multi- .plepoint, around the contacts 442, in the previously traced loop circuit,including the trunk 6| and extending between the line finder 4| and thesecretary connector 5|. Further the test relay R460 completes, at thecontacts 466, an obvious circuit for energizing the winding of thecutofi relay R450, thereby to cause the latter relay to operate andinterrupt, at the contacts L .a further point in the previouslytraced-circuit for energizing the vertical magnet M405. Finally, thetest relay R460 completes, at the contacts 464, aconnection, includingthe contacts 445 and 446, between 'the guard conductor C412 and therotary conductor C413 in the cable 410, thereby to complete .a circuit,including the contacts 224, 23|, .242, 25I and 223, and the wiper .202of the switching mechanism 200 and the engaged contact in the associatedcontact'banlg-for energizing the magnet M206. When thus energized themagnet M206 operates, thereby to condition the wipers noted of theswitching mechanism 200 to be driven an additional step in the clockwisedirection.

Also when the grounded rotary conductor C413 is thus connected to theguard conductor C412 in the line finder 4| 'as explained above, 'a path,including the wiper 202 of the switching mechanism 200 and the engagedcontact in theassociated contact bank, andthe contacts 223,201 and "221,is completed for short-circuiting the wind- 'ing of the test relay R220,thereby to cause the latter relay to restore. Upon restoring, the testrelay R220 interrupts, at the contacts 221, a point in the previouslytraced path for short-circuiting the winding thereof, and interrupts, atthe contacts 221, the previously traced path for applying groundpotential to the start aconductor C415 in the cable 4T0, thereby tointerrupt the previously traced circuit 'for energizing the winding ofthe start relay R440 in the line finder 4| in order to cause the latterrelay to restore shortly thereafter, the start relay R440 being of theslow-to-release type. Also, .upon restoring, the test relay R220interrupts, at the contacts 223, the previously traced circuit forenergizing the ."magnet M206, thereby to causethe latter magnet torestoreand .drive the wipers notedof the switching mechanism 200 anadditional step in the clockwise :direction in order "to disengage theconductors in itheca'ble 410 extending to the line Further thetest relayR220interrupts, at the contacts 225, the previously traced holdingcircuit for'energizing the upper Winding of thetransfer relay R240,thereby to cause the latter relay to restore. At this time the linefinder distributor 34 is completely released and is available forfurther use.

Upon restoring, the start relay R440 in the line finder 4-| interrupts,at the contacts 442, the previously traced original circuit forenergizing the lower winding of the test relay R460; however, the latterrelay remains in its operated position due to the previously tracedcompleted holding circuit for energizing thelower winding thereof,including the grounded control conductor 0220 of the subscriber line 22.Also the start relay R440 interrupts, at the contacts 44|, a

multiple point in the loop circuit extending bethe guard conductor C412in the cable 410 marks the line finder 4| as busy to the line finderdis,-

tributor 34, as previously noted. Accordingly, at this time, the wiperset of the switching mechanism 400 in the line finder 4| occupies its 2up 2 in position-engaging the'contact set in the associated contact bankterminating the subscriber line 22 extending to the .called subscribersubstation T2. Further'it is noted that the 2 up 2-in position of thewiper set of the switching mechanism 200 corresponds to the digits 2.and 2 representing the directory number of the :called subscribersubstation T2.

Reconsidering now the operation of the line finder 4| in conjunctionwith the line finder distributor 34, it is noted that each time the steprelay R230 in the line finder distributor 34 operates and then restoresit completes and then interrupts, at-the contacts 232, an'obvious path,including the wiper 205 of the switching mechanism 200 and the engagedcontact in the associated-contact bank, for applyingground potential tothe pulse conductor C411 in the cable 410,

thereby to complete and then to interrupt an obvious circuit forenergizing the winding of the pulse relay R420 in the line finder 4|,whereby the latter relay :operates :and then restores.

:Each time the pulse relay R420 in the line finder 4| operates and:thenrestores it interrupts and then recompletes, at the contacts 42l,the previously traced loop circuit extending "between the line finder 4|and the secretary connector 5|, including the trunk 6| whereby the linerelay R360 in the secretary connector 5| follows the pulse relay R420 inthe line finder 4|. In

view of the foregoing explanation of the mode of operation of the linefinder 4| in conjunction with the line finder distributor 34, it will beunderstood that the step relay R230 first-controls the vertical motionof the wiper set of the switching mechanism 400, whereby the wiper setis operated two steps in the vertical direction, in the 'the'presentexample, and'a corresponding numberof impulses comprising the digit 2are transmitted by'lthe step'relay R230 to the pulse relay R420 andrepeated thereby over the trunk 6| to the line relay R360. Hence, theline finder distributor 34 is operative to control the line finder 4! toselect the called subscriber line 22 and torepeatover the trunk 6| tothe line relay R360 in the secretary connector the two digits 2 and 2corresponding to the directory number of the called subscriber line 22.

Thefline relay R360 in the secretary connector 5| follows the' firstdigit 2 in an obvious manner; When the line relay R360 operated it'completed,'at the contacts 361, an obvious circuit for energizing thewinding of the hold relay R350,

whereby the latter relay operated; The first time the line relay R360restores it interrupts, at the contacts 36 I the previously mentionedcircuit for energizing the windingof the hold relay R350,

7 and completes, at the contacts 362, a circuit, in-

V cludingthe contacts and the contacts 309 of the set of switchspringsS308, for energizing the winding of the transfer relay R340 inseries'with the vertical magnet M304, whereby the transfer relay R340and the vertical magnet M304 the contacts 309 thereof, thepreviously'traced original circuit for energizing the winding of the"transfer relay R340 in Series with the vertical magnet M304 and thereis completed, atv the con-,

tacts 3l0 thereof, an alternative circuit, including the contacts 362,35land 342, for energizingthe winding of the transfer relay R340 inseries with the v'ertical'magnet M304. The first time the line relayR360 reoperates it recompletes,

V at the contacts 36I, the previously mentioned circuit foren'ergi'zing'the winding of the hold relay R350,and interrupts, at the contacts 362,the previously traced alternative circuit for energiz ing thelwin'dingof the transfer relay R340'in series with the vertical magnet .M304. Theline relay'R 360 restores and then reoperates twice, in .the presentexample, in response to the two impulses of the first digit 2transmitted over the trunk filfwhereby the vertical magnet M304 isoperated aridirestored twice in order to drive the wiper set of theswitching mechanism 300 two steps in the verticaldirection. The holdrelay The line relay R360 then follows the two 1mpulses of the seconddigit 2. 'Each timethe line relay'R350 restores it interrupts, at thecontacts 36!, the previously mentioned circuit for energizing thewinding of the hold relay R350, and completes, at the contacts 362,'thepreviously mentioned circuit, including the contacts 35!, the contacts3l0 of the set of switch springs S308, and the contacts 34| and 325, forenergizing the winding of the series relay R330 in series with therotary magnet M305. When thus energized the series relay R330 operates;and the rotary magnet M305 operates, thereby to drive the wiper set ofthe switching mechanism 300 one step in the rotary direction away fromits normal rotary position. Each timethe line relay R360 reoperates itrecompletes, at the contacts 361, the

previously mentioned circuit for energizing the winding of the holdrelayRj350, and interrupts, at the contacts 362, the previously tracedcircuit 7 for energizing in series the winding of the series relay R330and the rotary magnet M305.- The hold relay R350 andthe series relayR330 are of the slow-to-release type and remain operated 'duringimpulsin-g. At the conclusion of the second digit 2 transmitted over thetrunk 6! the line relayR3'60 remains in its operated position,

thereby to retain operated the hold relay R350;

and, shortly thereafter, the series relay R330 re- "stores. At this timetheowipef'SBt of the switching mechanism 300 engages the 2 up 2 incontact set in the associated contact bankv terminating the trunk 82which is terminated by the jack.J2 at the secretary operator positionII,

the trunk 82 and the terminating jack J2 corresponding to the subscriberline 22 extendingto thecalled subscriber substation T2 in the branchofiice 20, as previously noted. Upon restoring, the series relay R330:completes, at the contacts 33!, a circuit, including the wiper 303 ofthe wiperset of the switching mechanism 300 and the engaged contactIinthe associated contact bank, the control conductorof thetrunk B2 andthe contacts of the jack J2, for energizing in series the upperwindingof the switch relay R320 and the signal lamp L382.. When thissericscircuit is completed the switch relay'R320operates to complete, at the:contacts 324, an obvious holdi ing circuit, including the :contacts 353,for energizing the lower winding thereof. 'Also the switch relay R320interrupts, at the contacts 325,*a f urther point in the previouslytracedcircuit for energizing the Winding, of theseries relay R330 inserieswith the rotary magnet M305, and com pletes, at the contacts 323,an obvious path, including the contacts 33l,for short-circuiting theupper winding of the switch rela R320., Also i the switch re1ayR320completes, at the contacts R350 and the transfer relay R340, being ofthe *slow-to-r'elease type, remain operated during impulsing. Attheconclusionof the first digit 2, the line relay R360 remains operatedin order *to retain the hold relay R350 in its operated posi- 'tio'n,whereby-the transfer relayR340'restores shortly thereafter; Uponrestoring, the transfer tacts 34l, acircuittraced hereinafter'for energizing -the1windihg of the series relay R330 inseries with the rotarymagnet M305.- T s I V 323,"an-obvious .path forrapplying direct groundpotential 'to the wiper 303 of the wiper set of V the switchingmechanism'300, thereby to com plete a low resistance circuitsubstantially identif cal 'to that previously traced for illuminatingthesignal lamp L382. Finally the switch relay R320 completes, at thecontacts 32I and '322, an obivious connection, including the fwipers 3Mand 302 of the wiper set of theswitching mechanism 300, between theupper and lower windings of 7 the battery reverse relay R310 'andtheline conductors of the trunk terminating in' the jack 7 J2, with whichthe illuminated signal lamp L382 7 is associated. The illuminationof'the signal lamp L382 indicates .to the operator at the secretaryoperator position ll that'there is a call onthe V relay operates as itis of the polarized type.

trunk 82 waiting to be answered and. that, consequently, a call has'beenextended to or initiated,

at the called subscriber substation T2 in the branch oflice 20.

The operator at the secretary operator position answers the call byinserting the answer plug of the cord circuit into the jack J 2, wherebythe contacts of the jack J2 are operated in order to interrupt thepreviously traced circuit for illuminating the signal lamp L382, wherebythe last-mentioned lamp is extinguished. Also an operative connection iscompleted between the telephone instrument in the cord circuit at thesecretary operator position H and the line conductors of the trunk-'82,whereby an obvious loop circuit is completed for energizing in Seriesthe upper and lower windings of the battery reverse relay R310. Whenthus energized the battery reverse relay R310 operates to interrupt, atthe contac'ts312 and 314, the previously traced original loop circuitextending'be'tween the line relay R360 in the secretary selector 5| andthe answer relay R430 in the line finder 4| and to complete, at thecontacts 3H and 313, an obvious alternative loop circuit between theline relay R360 and the answer relay R430; whereby the direction ofcurrent flow over the loop circuit mentioned is reversed. When thedirection of current flow through the windings of the answer relay R430in the 'line finder 4| is thus reversed th latter Upon operating, theanswer relay R430 complete at the contacts 43|, a connection includingthe windings 438 and 439 of the repeating coil 43.5

between the wipers 40| and 4020f the wiper set of the switchingmechanism 400, whereby the windings 438 and 439 are operatively connectd to the line conductors of the subscriber lin 22 extending to thecalled subscriber substation T2. Accordingly, at this time, the callingsubscrib r substation TI is operatively connected via the subscriberline 2|, the local finder. 21, the local connector .28 and thesubscriber line 22t the called subscriber substation T2; and thesubscriber line 22 extending to the called subscriber substation T2 isoperatively connected .Via the line finder 4|, the trunk 6|, thesecretary con nector 5|, the trunk 82, the jack J2 and thecord circuit,to the telephone instrument at thesecrfi taryoperator position I,whereby the subscriber at the calling subscriber substation Tl in thebranch ofiice 20 may converse with the operator at the secretaryoperator position in .the central oflice ID. More particularly,theoperator at the secretary operator position L l answers .the call onthe trunk 82 and gives the subscriber at the calling subscribersubstation Tl the information which is to be given to calling subscribersubstations in the absence of thesubscriber at the called subscribersubstation T2, which is rendered secretarial service at this time. a

After the subscriber at the calling subscriber substation TI in thebranch oflice .20 has received the information mentioned from theoperator .at the secertary operator position H in the :central oflicel0, he replaces the receiver upon its associated switchhook; however,the local finder 21 and the local connector 28 remain in their'operatedpositions due to the operated position of the switching mechanism 400.The operator at the secretary operator position then withdraws theanswer plug of the cord circuit ,from the jack J2, thereby to interruptthe previously traced. loop circuit for energizing in series the upperand lower winding .of the battery reverse relay R310 in thesecretaryconnector 5|, whereby the latter relay restores. Upon restoring, thebattery greverse relay R310 in the secretary co-nnector 5| interrupts,at the contacts 315, apreviously completed multiple holding circuit forenergizing the winding of the hold relay R350, interrupts, at thecontacts 311 and 313, the prezviously traced alternativ loop circuitextending between the answer relay R430 in the line finder 4| and theline relay R360 in the secretary connector 5|, and completes, at thecontacts 312 and 314, the previously traced original loop circuitbetween the answer relay R430 and the line re.- lay R360. Accordingly,the direction of current fiow over the trunk 6| between the answer relayR430 in the line gfinder 41 and the line relay R360 in the secretaryconnector 5| i -reversed, whereby the answer relay R430 restores as itis of the po, larized type. Upon restoring, the answer relay R430interrupts, at the contacts .43|, the previously traced "loop circuitbetween the windings 43a and 43a of the repeating coil 435 and the localconnector 28, whereby the local finder 2-1 and the local connector 28are released.

When the local finder. 21 is thus =reelased the subscriber line 2|extending to the subscriber substation TI is marked as idle to the localconnectors having access thereto; and when the'local connector 28 isthus released the subscriber line 22 extending to :the subscriber.substation T2 is marked as idle to the local connectors having accessthereto. More particularly, when the local connector :28 is thusreleased, ground potential therein i "removed from the control conductor:CZZ'B of the subscriber line 22, thereby to interrupt the previouslytraced original circuit for energizin the winding of the start relayR565, the previously traced holding circuit for energizing the winding.of the cutoff relay R560 and the previously traced path for applyingground potential to the control conductor 02-20 of the subscriber 'line22. The start relay R565 and the cutoff relay R560 in the secretary linecircuit 32 restore; and the service relay R510 therein remains in itsoperated position, whereby secretarial service is maintained incforce atthe subscriber substation'T2. When ground potential is removed from thecontrol conductor 022C or the subscriber line 22 the previously tracedholding circuit for energizing the lower winding of the'test relay R460in the line finder 4| is interrupted, thereby to cause the latter relayto restore. Upon restoring, the test relay R460-completes, at thecontacts 463, a circuit, including. the contacts 443 and the set ofswitch springs S4'l3, for energizing the release magnet M409, wherebythe latter magnet operate in order to release the wiper set and thevertical control wiper 404 of the switching mechanism 400, wherebythewiper set is returned to its normal rotary and vertical positions andthe vertical control wiper 4:04 is returned to its normal verticalposition. When the wiper set of the switching mechanism 400 is thusreleased the sets of switch springs SM 0 and S4|3 are actuated; -Moreparticularly, the set of switch springs S4 |0-is actuated, whereby thereis interrupted,

at ,thE-gCOlltaQts 4|2 thereof, the previously traced path for. applyingground potential to the guard conductor C412 inthe cable 410 and thereiscompleted, at the contacts 4 thereof, the previously traced path forapplying battery potential by way of the lower winding of the test relayR460 to the guard. conductor C412 in the cable4'l0.

- The removal of ground potential from and the application of batterypotential to the guard conductor C412 in the cable 410 marks the linefinder 4| as idle to the line finder distributor 34, whereby the linefinder 4| may be preselected at this time by the line finder distributor34 for furtheruse. The set of switch'springs S4|3 is actuated intodisengagement, thereby to interrupt the previously traced circuit forenergizing the release magnet M409, whereby the latter magnet restores.

Also, upon restoring, the test relay R460 interrupts, at the contact46|,the previously traced loop circuit extending between the answerrelay R430 in the line finder. 4| and the line relay R360 in thesecretary connector 5|, whereby the line relay, R360 restores, theanswer relay R430 already occupying its restored position. Uponrestoring, the line relay R360 in the secretary connector 5| interrupts,at the contacts 36I, the previously mentioned circuit for energizing thewinding of the hold relay R350, thereby to cause the latter relay torestore shortly thereafter, the 7 hold relay R350 being of theslow-to-release type. Upon restoring, the hold relay'R350 interrupts, at

the contacts 353, the previously traced holding circuit forenergizingthe lower winding of the switch relay R320, thereby to causethe latter relay'to restore. Also the hold relay R350 completes, at thecontacts 352, a circuit, including the'contacts 362 and the set ofswitch springs $301, for energizing the release magnet M306, 7 therebyto cause the latter magnet to operate and release the Wiper set of theswitching mechanism 300, whereby the wiper set mentioned is returned 7 Vto its normal rotary and vertical positions. -When the 'wiper set oftheswitchingmechanism'300 is thus released the set of switch springs S301is actuated into disengagement, thereby to' 'interrupt the previouslytraced circuit'for energizing the release magnet C306 in order to causethe latter magnet to restore. At this time the secretary connector 5| iscompletely released and available for further use. 7

In view of the foregoing explanation it will be understood that therelease of the local connector 28 is eifected jointly by the subscriberat the calling subscriber substation T| in the branch office 7 20 and bythe operator at the answering secretary operator position I in thecentral ofilce l0,

whereby the local connector" 28 is not released until both thesubscriber at the calling subscriber substation Tl replaces the receiverupon its asso- 'ciated switchhook and the operator at the an sweringsecretary operator position I I withdraws the answer plug of the cordcircuit from the jack J 2. When the local connector 28 is thus releasedthe line finder. 2| and the secretary connector 5|,

' connected together via the trunk 6| to form' the link mentioned, arereleased, whereby the line finder 4| is marked aslidle to the switchingmechanism 200 in the line finder distributor 34.

In the foregoing explanation of the mode of operation ofthe line finder4| to 'find the subscriber line 22 extending to the called subscribersubstatidn T2 in response to the extension of the 'callthereto fromthecallin'g subscriber substati onT l, itwas assumed that the .line'finder 4| operated under the control of the lin finderdis tributor 34,whereby the wiper set of the switchcontrolled over the subscriber line22.

ing mechanism 400 found the contact set in :the associated contact bankterminating the subscriber line 22. some reason the Wiper set of theswitching mechanism 400 in the line finder 4| fails to find the contactset in the associated contact bank'terminating the subscriber line 22extending to the calledsubscriber substation T2 during itsoperation inthe'rotary direction. In this case, the

wiper setof the switching mechanism 400 is driven eleven steps in therotary direction away from its normal rotary position without efiectingoperation ofthe test relay R460, in the manner previously explained. Inthis case; the set of switch springs S4 l 4 isv actuated, whereby anobivous path, including the contacts 445, is completed for applyingground potential to the guardconductor C412 in the cable 410. Thisapplicationof ground potential to the guard conductor C412 in the cable410 completes a circuit,-includin the wiper 2-02 of the switchingmechanism 200'and the engaged contact in the, associated contact,

bank and the contacts 223, for energizing the magnet M206 and an obviousmultiple path, including the contacts 201 and 221, for shortcircuitingthe winding of the test relay-R220; whereby the magnet M206 operates andthe test relay R220 restores. Upon restoring, the test relay R220interrupts, at the contacts 223, the previously traced circuit forenergizing the mag net M206, thereby to cause the latter magnet torestore and drive the wiper set of the switching mechanism 200 anadditional steprin the clockwise direction. Thus the wiper set oftheswitching mechanism 200 is operated to disengage the contacts in theassociated contact bank terminating theconductors extending to the linefinder 4| and to engage contacts in the associated contact bank,terminatingconductors extending to another line finder 42 etc, wherebyoperation of the last-mentioned line finder is initiated to hunt for thesubscriber line 22- extending to the'called subscriber substation T2,=inthe manner previously explained, and the start relay R440 in the linefinder 4| restores in order to effect the release of this line finder inthe manner previously explained. Thus it will be understood that, in theevent any line finder preselected for use by the line finder distributor34 is first operated to hunt for thesubscriber line extending toa calledsubscriber substation rendered secretarial service and fails to findthesubscriber linementione'd,

the'line finder distributor operates in orderto assign another idle linefinder to hunt for the" called subscriber line mentioned, and thepreviously selected. line finder is released.

Discontimu'ng secretarial service at asubscriberv substation in thebranch office substation T2, the subscriber thereat firstinitiates -acall by removing the receiver from its associated switchhook;whereby'the local line circuitj25 is More particularlyftheilocal linecircuit 25 is controlled in orderto cause ground potential to be appliedto the control conductor 022B of the subscriber line 22in order to markthe subscriber line 22 as busy to the local connectors having accessthereto, as

previously explained. This application of ground potentialto'the'control' conductor C223 'o'fthe However, it may occur that forFor example,'in order subscriber. line 22 completes the previouslytraced circuit for energizing the winding of the start relay R565 in thesecretary line circuit 32, where,- by the latter relay operates. Uponoperating, the start relay R565 initiates operation of the line finderdistributor 34, whereby an idle line finder,

such, for example, as the line finder 4 I is assigned in the mannerpreviously explained. The line finder 4| then operates in order to findthe sub scriber line 22 having a call thereon extending to the callingsubscriber substation T2; whereby operation of the associated secretaryconnector 5i is controlled over the trunk 6| to seize the trunk 82terminating in the jack J2 at the secretary operator position I] in thecentral ofiice l0, all in the manner previously explained. The operatorat the secretary operator position H then answers the call on the trunk82 and converses with the subscriber at the calling subscribersubstation T2 in the branch office 20. The subscriber at the callingsubscriber substation T2 then advises the operator at the secretaryoperator position l l that the secretarial service being rendered thesubscriber substation T2 is no longer required. The subscriber at thecalling subscriber substation T2 then replaces the receiver upon itsassociated switchhook; and the operator at the secretary operatorposition ll withdraws the answer plug of the cord circuit from the jackJ2; whereby the established connection is released in the mannerpreviously explained.

The operator at the secretary operator position ll then inserts the callplug of .the cord circuit into the jack J l2 terminating the trunk 12extending between the central office l0 and the branch ofiice 20, thetrunk 12 being terminated in the secretary service switch H, aspreviously explained. The operator at the secretary operator position Hthen dials three digits over the trunk 12; the first digit beingeffective to operate. the select switch 520 in order to indicate thatsecretarial service is to be discontinued. and the second and thirddigits being effective to operate the switching mechanism 500, therebyto select the secretary line circuit 32 associated with the subscriberline 22 extending to the subscriber substation T2. More particularly, inthe present example, in order to discontinue secretarial service at thesubscriber substation T2, the three digits 2, 2 and 2 are dialed; thefirst digit 2 indicating that secretarial service is to be discontinuedat a subscriber substation and the second and third digits 2 and 2,respectively, identifying thesecretary line circuit 32 individual to thesubscriber line 22 extending to the subscriber substation T2. Moreparticularly, the secretary service switch H operates in response to thethree digits 2, 2 and 2, in the manner previously explained, and, at theconclusion of the operation thereof, the control relay R555 restores,thereby to effect operation of the switch relay R550 in .the mannerpreviously explained. Upon operating, the switch relay R550 completes,at the contacts 552, the previously traced holding circuit forenergizing the lower winding thereof and completes, at the contacts 55!,the previously traced path for short-circuiting the upper windingthereof and for applying direct ground potential to the wiper 52l of theselect switch 520, whereby ground potential is applied to the wiper 502of the wiper set of the switching mechanism '500 and the engaged contactin the associated contact bank terminating the conductor C582. Theapplication of ground potential to the conductor C582 completes anobvious path, including the contacts 511, for short-cirouiting thewinding of the service relay R510 in the secretary line circuit 32,thereby to cause the latter relay to restore. Upon restoring, theservicere lay R510 interrupts, at the contacts 5', a further point inthe previously traced holding cire cuit for energizing the windingthereof, and in,- terrupts, at the contacts 512, the previously tracedconnection between the winding of the start relay R565 and the controlconductor 0223 of the subscriber line 22. After the operator at thesecretary operator position H has thus dis,- continued secretarialservice at the subscriber substation T2, she withdraws the call plug oithe cord circuit from the jack J l2, thereby to eifect the release ofthe secretary service switch I l, in the manner previously explained. Atthis time, secretarial service at the subscriber substation T2 isdiscontinued and this subscriber substation is rendered ordinarysubscriber sub,- station service at this time.

Local calls in the branch oflice .ciated secretary line circuit 32 theservice relay R510 occupies its restored position, whereby the windingof the start relay R565 therein is disconnected from the controlconductor C22B of the subscriber line 2-2 extending'to' the subscribersubstation T2.

Conclusions In view of the foregoing it is apparent that a telephonesystem is provided which comprises a central office and a branch oilice;which system includes'improvedapparatus for rendering secretarialservice to a relatively large group of subscriber substations inthe'branch ofiice from a secretary operator position in the centralvoflice via a relatively small number of links ,or trunks extendingbetween .the branch .ofiice .and the central ofiice.

While one embodiment of the invention has been disclosed, it will beunderstood that various modifications may be made therein which arewithin the true spirit and scope of the invention.

What is claimed is:

1. In a telephone system, a calling station, a plurality of lines, meansfor extending lacall from said calling station to any called one .ofsaid lines, a link, an operator position, .means controlled from saidoperator position for selecting any one of said lines and characterizingthe selected line, line identity apparatus associated with said operatorposition, and means controlled by the extension of a call to anycharacterized one of said lines for setting up a connection .jrom saidone characterized line by way of said link to said operator position andfor selectively operating said line identity apparatus tojid entify saidone characterized line.

2. In .a .telephone system, a calling station, a

plurality of lines,- means 'for extending a call from said callingstation to any called one of said lines, a plurality of links fewer innumber than said lines, an operator position, a numerical switch, meansat said position for operating said switch directively thereby tocharacterize any desired one of said. lines, line identity apparatusassociated with said operator position, and means controlled :by theextension of a call to any characterized one of said lines for settingup a connection from said one characterized line by way of an idle oneof said links to said operator position and for selectively operatingsaid line identity apparatus to identify said one characterized line;

3. In a telephone system, a calling station, a plurality of lines,automatic switching apparatus selectively'controllable from said callingstation to extend a call therefrom to any called one of 7 said lines, anautomatic switching link, an operator position, means controlled fromsaid operator position for selecting any one of said lines 7 andcharacterizing the selected line in either of two ways, line identityapparatus associated with said operator position, and means controlledby the extension of a call to any called one of said lines only if saidcalled line is characterized in 'a particular one of said two Ways forselectively operating said switching link to set up a connection fromsaid one called line to said operator position and for selectivelyoperating said line identity apparatus to identify said one called line.

4. In'a telephone system, a calling station, a plurality of lines, meansfor extending a call from said calling station to any called one of saidlines, an operator switchboard, a plurality of trunks accessible 'tosaid operator switchboard and individually corresponding to said lines,an automatic switch having access to said trunks, means controlled bythe extension of a call to any called one of said lines for selectivelyoperating said switch to select the one of saidtrunks corresponding tosaid one called line, thereby to initiate a' call on said one trunk,means control- 7 lable from said operator switchboard for answering thecall on said one trunk, and means for connecting said switch to said onecalled line.

In a telephone system, a calling station, a plurality of lines, meansfor extending a call from said calling station to any called one of saidlines, an operator switchboard, a plurality of trunks accesible to saidoperator switchboard and individually corresponding to said lines, anautosaid second switch to select the one of said trunks corresponding tosaid one called line, thereby to initiate a .call on said one trunk,means controllable from said operator switchboard for answering the callon said one trunk, and means for connecting together said first andsecond switches.

'7. In a telephone system, a calling station, a plurality of lines,means for extending a call from said calling station to any called oneof said lines, a first automatic switch having access to said lines, anoperator switchboard, a plurality of trunks accessible to said operatorswitchboard and individually corresponding to said lines, a

second automatic switch having access to said trunks, means controlledby the extensionof a call to any called one of said lines forselectively operating said first switch to select said one called lineand for selectively operating said second switch to select the one ofsaid trunks corresponding to said one called line, thereby to initiate acall on said trunk, means controllable from said operator switchboardfor answering the call on said one trunk, and means controlled bytheanswering of the call on said one trunk for connecting together saidfirst and second switches.

8. In a telephone system, a calling station, a plurality of lines, meansfor extending a call said lines, a first automatic switch having accessmatic switch having access to said trunks, means 7 controlled by theextension of a call to any called one of said lines for selectivelyoperating said switch to select the one of said trunks corresponding tosaid one called line, thereby to initiate a call on said one trunk,means controllable from said operator switchboard for answering the callon said one trunk, and means controlled by the answering of the call onsaid one trunk for connecting said switch to said one called line.

6; In a telephone system, a calling station, a plurality of' lines,means for extending a call from said calling station to any called oneof said lines, a first automatic switch having access to said lines, anoperator switchboard, a plurality of trunks accessible to said operatorswitchboard and individually corresponding to said lines, a secondautomatic switch having access to said trunks, means controlled by theextension of a call to any called one of said lines for selectivelyoperating operating said first switch to select said one called line andfor selectively operating 7 to said lines, an operator position, asecond automatic switch, means controlled by the extension of a call toany called one of said lines for selec- V tively operating said firstswitch to select said 7 one called line and for selectively operatingsaid second switch correspondingly, means controlled by the operation ofsaid second switch for extending a call to said operator position andfor identifying said one called line, means controllable from saidoperator position for answering the call extended thereto, and means forconnecting together said first and second switches.

9. In a'telephone system,.a calling station, a plurality of lines, meansfor extending; a call from said calling station to any called one ofsaid lines, a plurality of links, an operator position, means controlledby the extension of a call to any called one of said lines for extendinga call from said one called line by way of an" idle one of said links tosaid operator position, means controlled by the extension of a call oversaid one link for rendering it busy, means controllable from saidoperator position for answering the call on said one link, and meanscontrolled jointly by the performance of a release operation at saidcalling station and by the performance of a release operation at saidoperator position for rendering said one link again idle.

10. In a telephone system, a calling station, a plurality, of lines,means forextending a call from said calling station to any called one ofsaid lines, a link, an operator position, line identity apparatusassociated with said operator position, means controlled by theextension of a call to any called one of said lines for extending a callover said link to said operator position a trolled by the answering ofthe call on said link for connecting said link to said one called line.

11. In a telephone system, a calling station, a plurality of lines,means for extending a call from said calling station to any called oneof said lines, a link, an operator position, line identity apparatusassociated with said operator position, means controlled by theextension of a call to any called one of said lines for extending a callover said link to said operator position and for transmitting a signalover said link individual to said one called line, means controlled bythe signal transmitted over said link for selectively operating saidline identity apparatus to identify said one called line, meanscontrollable from said operator position for answering the call on saidlink, and means controlled by the answering of the call on said link forconnecting said link to said one called'line.

12. In a telephone system, a calling station, a plurality of lines,means for extending a call from said calling station to any called oneof said lines and for initiating the projection of ringing currentthereover, a link, an operator position, line identity apparatusassociated with said operator position, means controlled by the.extension of a call to any called one of said lines for extending acall over said link to said operator position and for selectivelyoperating said line identity apparatus to identify said one called line,means controllable from said operator position for answering the call onsaid link, means controlled by the answering of the call on said linkfor connecting said link to said one called line, and means controlledby the connection of said link to said one called line for arresting theprojection of ringing current thereover.

I 13. In a telephone system, a calling station, a plurality ofsubstations, automatic switching apparatus selectively controllable fromsaid calling station to extend a call therefrom to any called one ofsaid substations, an operator position provided with facilities forrendering secretarial service to said substations, apparatus temporarilyoperated under the control of said position to select any desired one ofsaid substations, means controlled by said apparatus for characterizingthe selected substation and maintaining it characterized after saidapparatus has restored to normal at the end of its temporary operation,and means controlled by the extension of a call to any one of saidsubstations so characterized for setting up a connection from said onecharacterized substation to said operator position.

14. In a telephone system, a first ofiice including a calling station, aplurality of substations, and means for extending a call from saidcalling station to any called one of said substations; a second ofliceincluding an operator position provided with facilities for renderingsecretarial service to said substations; two trunks extending betweensaid ofiices; means controllable over a particular one of said trunksbut not over the other of said trunks for conditioning any one of saidsubstations to receive secretarial service; and means controlled by theextension of a call to any one of said substations which is thusconditioned for setting up a connection from said one called substationby way of the other of said trunks to said operator position.

15. In a telephone system, a first office including a calling station, aplurality of substations, and means for extending a call from saidcalling station to any called one of said substations; a second oiificeincluding an operator position provided with facilities for renderingsecretarial service to said substations, and substation identityapparatus associated with said operator position; two trunks extendingbetween said offices; means controllable over a particular one of saidtrunks but not over the other of said trunks for conditioning any one ofsaid substatios to receive secretarial service; and means controlled bythe extension of a call to any called one of said substations which hasbeen thus conditioned for setting up a connection from said one calledsubstation by way of the other of said trunks to said operator positionand for selectively controlling said substation identity apparatus oversaid other trunk to identify said one called substation.

16. In a telephone system, a calling station, a plurality of lines,means for extending a call from said calling station to'any called oneof said lines, an operator position, line identity apparatus associatedwith said operator position, a switch controllable from said operatorposition to select any one of said lines, means including said switchoperated at times to institute interceptor service upon any selected oneof said lines and operated at other times to discontinue interceptorservice upon any selected one of said lines, and means controlled by theextension of a call to any called one of said lines upon whichinterceptor service is in force for setting up a connection from saidone called line to said operator position and for selectively operatingsaid line identity to identify said one called line.

17. In a telephone system, a calling station, a plurality of'llnes,means for extending a call from said calling station to any called oneof said lines, a plurality of relays individually associated with saidlines, each of said relays including an operated position and a restoredposition and being provided with an operating circuit and a stickcircuit and a path for shorting its stick circuit, means for selectivelycompleting the operating circuits and the paths of said relays, meanscontrolled when any one of said relays occupies its two positionsrespectively to institute and to discontinue interceptor service uponthe associated line, an operator position, and means controlled by theextension of a call to any called one of said lines upon whichinterceptor service is in force for setting up a connection from saidone called line to said operator position.

18. In a telephone system, a calling station, a plurality of lines,means for extending a call from said calling. station to any called oneof said lines, a plurality of relays individually associated with saidlines, each of said relays including an operated position and a restoredposition and being provided with an operating circuit and a stickcircuit and a path for shorting its stick circuit, an automatic switchoperable selectively to complete the operating circuits and the paths ofsaid relays, an operator position, means controllable from said operatorposition for selectively operating said switch, means controlled whenany one of said relays occupies its two positions respectively toinstitute and to discontinue interceptor service upon the associatedline, and means controlled by the extension of a call to any called oneof said lines upon which interceptor service is in force for setting upa connection from said one called line to said operator position.

19. In a telephone, system, a substation, means for extending a call tosaid substation, means for extending a call from said substation, meansselectively controllable to institute and to discontinue interceptorservice at said substation, an operator position, and means controlledby the extension of all calls either to or from said substation wheninterceptor service is in force there-

